Applying a Rankine cycle, including an organic Rankine cycle, to an internal combustion engine may offer a fuel economy improvement by capturing a portion of heat energy that normally would be wasted in an internal combustion engine. However, control and operation of the system throughout an engine's transient duty cycle and through changing environments is challenging. Increasing the flexibility of operation of a WHR system may assist operation of the WHR system through an engine's duty cycle and through changing environments.